摘要:

To characterize the role of Ca2+in cholinergic stimulation of lacrimal gland protein secretion, the effects of inhibitors of cellular Ca2+handling on protein secretion were investigated. Protein secretion was measured from rat exorbital glands using either pieces of gland in perifusion or acini isolated by collagenase digestion. Peroxidase was used as a measure of protein secretion. An inhibitor of Ca2+influx via voltage sensitive Ca2+channels (verapamil) at 10−5and 5×10−5M did not alter protein secretion stimulated by the cholinergic agonist carbachol at. 10−5M. Inhibition of Ca2+efflux via Na+/Ca2+exchange by removal of extracellular Na+or by inhibition of Na+-K+-ATPase activity using ouabain (10−3M) or extracellular K+removal did not stimulate protein secretion. In contrast, inhibition of Ca2+release from intracellular stores with TMB-8 at 100μm completely blocked protein secretion stimulated by carbachol at 10−5M. Similarly, the Ca2+/calmodulin (CaM) antagonists W-13 and W-12decreased carbachol-induced proteinsecretion with potencies similar to those which inhibit Ca2+/CaM dependent processes. We conclude that cholinergic agonists stimulate lacrimal gland protein secretion primarily by mobilizing Ca2+from intracellular stores and that one mechanism by which this Ca2+could activate secretion is in conjunction with calmodulin.

ISSN:0271-3683    

DOI:10.3109/02713688509025163

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Secretion in tears has been investigated for a limited number of drugs. Transfer of the free non protein-bound fraction from plasma to tears only can be expected for unionized drugs with sufficient lipid solubility. For acid and basic drugs the correlation of tear: plasma (unbound) ratio is disturbed by variations in tear pH.Within these limitations tear sampling will not be an useful method for drug concentration measurement.

ISSN:0271-3683    

DOI:10.3109/02713688509025164

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

After certain tear proteins had been found to be markers of duct cell activity in the rabbit lacrimal gland, different secretagogues were tested to increase volume and protein secretion. Carbamyl-choline and the peptides eledoisin and vasoactive intestinal peptide (VIP) stimulated volume flux as well as secretion of the marker proteins indicating duct cell activation.β-adrenergic stimulation also increased secretion of a further tear protein. This might indicate that water is secreted by the duct cells. These are stimulated by the secretagogues mentioned above.β-adrenergic stimulation might in addition activate the acinar cell system.

ISSN:0271-3683    

DOI:10.3109/02713688509025165

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The tight junctions of the ciliary epithelium act as a barrier preventing the passage of blood borne macromolecules into the posterior chamber. The use of the freeze-fracture technique has led to a good knowledge of their morphological pattern in various species. However, in order to attempt a correlation of the morphology of the tight junctions with their physiological properties, their intimate substructure must be considered.As in other glutaraldehyde-fixed epithelia, the tight junctions appear as networks (variable in their apico-basal thickness) of more or less discontinuous P-face ridges and as complementary E-face furrows in which some particles or short bars are found. The significance of the discontinuities of ridges has been analysed. The continuity of the junctional fibrils was evident as assessed both by quantitative measurements as well as morphological examination of complementary fracture faces. In addition, the absence of loss of junctional material showed that the integrity of the junction was preserved during the freeze-fracture process, even in conditions where an increase in“transfer”of junctional elements was experimentally induced. Most of all, a“pore system”due to visualizable gaps in the fibrils is not tenable for the ciliary epithelium. Furthermore, the analysis of transition steps at the level of membrane“fusion”showed that the tight junctions of the ciliary epithelium must now be considered as formed by two slightly offset fibrils, one per adjacent plasma membrane.

ISSN:0271-3683    

DOI:10.3109/02713688509025166

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

We have either introduced into the vitreous space or perfused through the anterior chamber of macaque monkey eyes two anionic tracers, anionic ferritin (AF) and horseradish peroxidase (HRP) and a cationic probe, cationic ferritin (CF). We have observed that the anionic molecules, but not the cationic one, are transported to the blood stream by plasmalemmal vesicles of the endothelial cells in both the retinal and the iridial vasculature. We suggest that a variety of organic anions of different MW which are commonly present in the eye tissues may be returned to the blood by the same morphological mechanism.

ISSN:0271-3683    

DOI:10.3109/02713688509025167

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Methods were developed to isolate non-pigmented ciliary epithelium from bovine eyes (BCBE) free from other cell types in the ciliary process. Once background binding due to pigment was minimized, it was possible to assay specific beta adrenergic receptors in these preparations. The BCBE beta adrenergic receptors showed appropriate stereospecificity and an order of binding affinities compatible with a beta2 adrenergic selectivity. Interestingly, specific high affinity muscarinic cholinergic receptors were detected in both BCBE and primate non-pigmented ciliary epithelium. These muscarinic receptors showed an appropriate affinity and selectivity for agonists and antagonists.Further evaluations of the receptors and responses of non-pigmented ciliary epithelial cells may prove useful in understanding the effects of adrenergic and cholinergic agents on aqueous humor inflow.

ISSN:0271-3683    

DOI:10.3109/02713688509025168

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Epinephrine, isoproterenol and norepinephrine (10−6M−10−4M) reduced the short-circuit current (SCO across the isolated rabbit iris-ciliary body when added to the blood side (pigmented layer) bathing solution but were without effect when added to the aqueous side (non-pigmented layer) bathing solution. The effect was observed in both HCO−3-rich and HCO−3free solutions, although it was smallep in the latter. Propranolol and phentolamine (10−5M) partially blocked the action of the adrenergic agonists, 8Br-cAMP (1 mM), on the other hand, stimulated the SCC when added to either bathing solution. The apparent contradiction between these results is explained on the basis of separate cyclic AMP compartmentalization in the two epithelial cell layers and the lack of adrenoceptors in the non-pigmented layer.

ISSN:0271-3683    

DOI:10.3109/02713688509025169

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0271-3683    

DOI:10.3109/02713688509025142

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor